GLUT Flickering

I am creating a 3D game FPS, blah, blah, blah... BUT, when I run it my 'flats' (cuboids+imagination ) go, all, flickery? Not really flickery, more like for a split-second the bottom half of the flat moves to the left, and vice versa. This only happens if I'm moving the mouse and keying w,s,a or d (movement). Is this something to do with framerates?

PS. I tried to record a video, but it goes back to normal when I record! This could be because the app slows down the CPU, or something else.